The invention relates to a skin cleansing device for cleansing facial skin in particular, the skin cleansing device comprising a facial mask, two or more electrodes to be attached to the facial mask, a cleansing signal generator for generating an electric cleansing signal, and means for conveying the cleansing signal from the cleansing signal generator to the electrodes.
Cleansing methods mainly of three different types are nowadays used for cleansing human facial skin. The first method is based on utilizing different cleansing solutions and cleansing creams. In the method, cleansing solution absorbed in a piece of cotton, for example, is brought into contact with the skin in order to wipe the skin and dissolve impurities from the surface thereof. If the cleansing solution is to be left on the skin for a longer time to provide deeper cleansing and a more effective cleansing effect, the cleaner can be made more solid by combining it with a thicker cream or gel.
The second method is called exfoliation and it is based on using so-called exfoliating agents. In this method, a cleanser containing an abrasive material to mechanically rub the surface of the skin is spread on the skin. Exfoliation mechanically removes cell layers from the surface of the skin but leaves layers located deeper in the skin uncleansed.
The third method is based on utilizing the cooperative effect of a dissolving cleansing solution and electric current as the cleansing method. A cleansing solution is then used wherein the effective agents are electrically charged molecules, or ions. By bringing electric current into contact with the cleansing solution spread on the skin, the ions are made to move and transfer molecules of the cleanser into the skin, and, on the other hand, to transfer away from the pores impunties dissolved from the skin by the cleansing solution and to be removed therefrom. Hence, the skin purifying effect of the cleansing method can be improved and the deeper layers of the skin purified. The electric current is generated by a cleansing signal generator developed for the purpose, and it is conveyed to the skin by electrodes arranged in connection with a treatment towel or the like absorbing the cleansing solution and being preferably shaped according to the contours of an area in the skin to be treated.
Devices are previously known wherein pharmaceuticals or other conditioning agents are transferred into the body through the skin based on electrically charged molecules of the pharmaceuticals or conditioning agents and electric current. For example, U.S. Pat. No. 5,443,441 describes such a device. The purpose of the device is to transfer cosmetic conditioning agents into the skin by utilizing electric current. Also other devices are known that operate on a similar principle. In these devices, the current used for the treatment is usually direct current since the active agent is to be transferred in one direction only. Furthermore, devices are previously known wherein electric current or electric voltage is used in activating and rehabilitating muscles.
It can be generally stated, however, that the known devices and methods usually focus on transferring pharmaceuticals and cosmetic agents through the skin, activating muscles, improving the appearance or condition of the skin or tissues under the skin using at least partly mechanical means, even though these devices use electric current to generate a mechanical motion. The known devices are characterized in that they are developed to be used by professionals and experts in the field, which means that in order to achieve a favourable response and adequate user and patient safety, the users must have a proper knowledge of the treatment method used and the operation of the device; therefore, the devices are not suitable for non-professional use.
The known devices utilizing electric current usually use at least two electrodes, at least one electrode being attached to the body at a relatively long distance from the area of the skin to be treated. This means that in the body the electric current travels the distance between the electrodes, and, if alternating current is used, a risk exists that the alternating current travelling in the body might cause a serious heart dysfunction. When devices and methods based on direct current are used, the negative electrode is attached to a given point in the body, in which case the current travels via the same area in the skin throughout the entire treatment process. At said point, the relative current density may become high and the time of exposure long, which may cause hypersensitivity reactions to both electricity and manufacturing materials of the electrodes particularly at the points where the electrodes come into contact with the skin.
Since the known devices are intended for professionals, an average domestic user may often find them too expensive.
An object of the present invention is to implement a skin cleansing device so as to alleviate the above-mentioned problems and to provide a simple, easy-to-use, safe and inexpensive device particularly for skin cleansing for domestic use. This is achieved by a skin cleansing device disclosed in the preamble, the skin cleansing device being characterized in that the electrodes to be attached to the facial mask are arranged as electrode pairs comprising the positive electrode and the negative electrode, all electrode pairs are located in the facial mask substantially in the facial area, and the cleansing signal generated by the cleansing signal generator is an alternating current signal having substantially the shape of a square wave.
Preferred embodiments of the invention are disclosed in the dependent claims.
The idea underlying the invention is that by arranging the electrodes to be attached to the facial mask as electrode pairs comprising the positive electrode and the negative electrode and by placing all electrode pairs in the facial mask substantially in the facial area, several advantages improving the cleansing efficiency, user-friendliness and safety of the skin cleansing device are achieved.
When all electrodes are located in the area of the skin to be cleansed and when they are placed in the facial mask, the user is provided with a simple and easy-to-use mask structure which can be held in place throughout the entire cleansing process. In addition, as all electrodes are located in the area of the skin to be cleansed, the electric cleansing signal used by the cleansing device only affects in the area of the skin to be cleansed, which has the advantage that the electric current travels in the body only in the area to be cleansed. Hence, the signal does not have to travel a long distance in the body, so it is unable to stress or harm the action of other tissues or the heart. Neither can the electric signal then cause a hypersensitivity reaction, thus improving the safety of the device as a treatment device.
Arranging the electrodes as electrode pairs has the advantage that the electrodes can be formed so as to have a preferred size and shape in regard to the area of the skin to be treated. For example, in the area of the forehead and the chin, the electrodes have a different preferred size and shape. A further advantage is that the active cleansing signal in the area of an electrode pair remains regional, thus improving the cleansing efficiency.
In a skin cleansing device of the invention, a cleansing signal which is generated by a cleansing signal generator and which is an alternating voltage signal having the shape of a square wave is used to provide an electric cleansing effect, i.e. to make the ions in the cleansing solution move. The ions in the cleansing solution are then engaged in an alternate backward and forward motion, which has the advantage that by the positive current impulse, positive ions of the cleansing solution are transferred deeper in the skin through the surface of the skin, while by the negative current impulse, correspondingly, the positive ions are transferred from the skin or vice versa, depending on the charge of the ion. Hence, the cleansing effect is enhanced since the device both transfers the cleansing solution to the skin and transfers impurities dissolved by the cleansing device from the skin. In skin cleansing, a preferred cleansing effect to yield adequate penetrability into the pores is achieved at a frequency of about 2000 Hz. A further advantage of this frequency is that it is sufficiently high so as not to harm the action of the heart.
In the skin cleansing device of the invention, the signal generated by the cleansing signal generator is substantially of the shape of a square wave. An advantage of the square wave is its high efficiency. The time taken by the skin cleansing process per a cleansing session can then be kept short. Furthermore, it has been found out that the third and the fifth harmonic wave in the square wave produce preferred cleansing effects. The voltage of the signal generated by the cleansing signal generator is lower than 5 V. A voltage of this magnitude is sufficiently low to be safe, producing, however, an adequate skin cleansing efficiency.
The facial mask of the skin cleansing device of the invention has a sandwich construction. A layer to be arranged against the face is manufactured of a substantially absorbent material with high receptivity of the cleansing solution, such as terry cloth, paper or some such material with high absorbency or a combination thereof. For a good cleansing efficiency, it is important that the material of the facial mask is capable of receiving a sufficient amount of the skin cleansing solution, and, in addition, feels comfortable against the face. Electrodes having a conductive contact with the cleansing solution are connected to a layer to be arranged on top of the absorbent layer, which can be manufactured of dense cloth, for example. A layer manufactured of a substantially more rigid material, such as plastic, serves as the outer surface layer of the mask. An advantage of this solution is that the facial mask is strong and easy to clean, and it enables the use of disposable components as the layer receiving the cleansing solution, for example.
In an implementation according to an embodiment of said skin cleansing device, the electrodes are manufactured of substantially chloridized silver. As a noble metal, silver is safe, causing no hypersensitivity reactions on the skin. Chloridized, a silver electrode has excellent electrical conductivity when used particularly as electrodes.
The skin cleansing device of the invention operates on low voltage direct current. Hence, being particularly designed for domestic skin cleansing use, an advantage of the skin cleansing device of the invention is its safety.